1. Field of the Invention
The present invention relates to a head member mounting and removing mechanism for detachably mounting a head member, and a recording apparatus provided with such head member mounting and removing mechanism.
2. Related Background Art
A recording apparatus having the function of a printer, copying machine, facsimile apparatus, or the like or a recording apparatus used as an output device of a complex electronics equipment or a work station, including a computer, word processor, or the like, is structured to record images on a recording material (recording medium) such as paper sheet or thin plastic sheet in accordance with image information. Depending on recording methods, such recording apparatuses are divided into those of ink jet recording type, wire-dot type, thermal type, laser beam type or the like.
For these recording apparatuses, a recording head is mounted on a head mounting unit (a carriage that moves a recording head serially if it is used for a serial printer, for example), and generally, the recording head is detachably mounted on the head mounting unit for the maintenance of the head, among others.
Hereunder, the description will be made of one conventional example of the head member mounting and removing mechanism for detachably mounting a recording head on a head mounting unit.
The recording apparatus described below is an ink jet type recording apparatus (an ink jet recording apparatus) that executes recording by mounting an ink jet recording head on its head mounting unit for recording by discharging ink from the ink discharge ports onto a recording medium. With an ink jet recording head of the kind, it is possible to execute recording of color images in high precision at higher speeds with lesser noises as the advantages and features thereof, and also, perform such recording at lower running costs. Further, as energy generating elements used for discharging ink, electrothermal transducing elements or electromechanical transducing elements are usable, but, particularly, a head using electrothermal transducing elements can be made more compact by the utilization of the semiconductor fabrication processes.
FIGS. 12A to 12D show types of a head cartridge integrally formed with an ink tank, which is regarded as one mode of an ink jet recording head of such kind as described above (hereinafter referred to as a recording head).
As shown in FIGS. 12A to 12D, a recording head 7 comprises an ink tank 73 and a head unit 71. The ink tank 73 is filled with a sponge impregnated with ink. For the head unit 71, there are arranged on an aluminum base plate 72, a silicon plate having a plurality of nozzles in a density of 360 per inch, heater elements, electrodes, and electric wiring formed on the plate, and a head substrate, a liquid chamber, an ink filter, an ink supply tube, and others.
As a structure to mount a recording head 7 such as described above on a recording apparatus main body, there has been proposed in Japanese Laid-Open Patent Application No. 7-251547 a structure which will be described below.
FIGS. 13A to 13C are front views of the carriage unit having a recording head 7 shown in FIG. 12 mounted on it. FIGS. 14A and 14B are front views which show a mounting and removing mechanism for the recording head 7: FIG. 14A illustrates the state where the head is set; and FIG. 14B illustrates the state where the head is released. FIG. 15 is a side view which illustrates the structure of the contacting portion and others of the carriage unit.
As shown in FIGS. 13A to 13C, a head holder 51 that serves as a unit for holding the head is structured to mount the recording head 7 on it along a guide (not shown) arranged on the carriage 50, and to make it slidable in the left and right directions as looking at FIGS. 13A to 13C. For the head holder 51, a pressure unit 512 is provided to press the recording head 7 to the contact surface 503 and the positioning surface 504 (see FIG. 15) of the side plate 502 that forms one side portion planted vertically on the guide unit 511 in order to guide the recording head 7 and the carriage 50. Also, a guide arm 513 is arranged in a position opposite to the pressure unit 512 of the head holder 51. This guide arm 513 acts upon the recording head 7 when the head 7 is parted from the contact surface 503.
An operational hook lever 53 is rotatively fixed to the side plate 502 of the carriage 50. On the rotational center of the hook lever 53, a contact spring 54 is arranged to bias the hook lever 53 in the direction indicated by an arrow in FIGS. 13A to 13C. A hook cover 55 is fixed to cover the hook lever 53 so as not to allow the hook lever 53 to fall off from the carriage 50. As shown in FIG. 14A and 14B, the hook lever 53 and the head holder 51 are respectively provided with cams 516 and 531 that can abut upon each other. It is arranged that with the rotation of the hook lever 53, the head holder 51 is caused to shift in the left and right directions as looking at FIGS. 14A and 14B. Also, the biasing force of the contact spring 54 is exerted through the hook lever 53 to press the recording head 7 on the head holder 51.
As shown in FIG. 15, on the side plate 502 of the carriage 50, positioning fixtures 505a and 505b are arranged to position the recording head 7. Further, a contact unit is provided for the side plate to make the electrical contact possible with respect to the recording head 7.
Now, with reference to FIGS. 13A to 13C, the description will be made of the mounting and removing operations of the recording head 7 on and from the carriage 50 structured as described above.
In order to mount the recording head 7, the hook lever 53 is raised in the upper direction in FIG. 13B as looking at FIG. 13B so that the head holder 51 is caused to shift to the left to make it ready for a recording head to be mounted. In this state, the recording head 7 is mounted, and then, the hook lever 53 is rotated in the lower direction in FIG. 13A as looking at FIG. 13A to cause the head holder 51 to shift to the right side together with the recording head 7. In this way, the recording head 7 is positioned to make the electrical contact and related operations possible. In this state, the image formation is ready for a sheet material P to be used.
On the other hand, when the recording head 7 is removed from the carriage unit 15, the hook lever 53 is again raised in the upper direction in FIG. 13B as looking at FIG. 13B so as to shift the head holder 51 to the left side. Thus the guide arm 513 of the head holder 51 presses the recording head 7 to the left side, and then, the recording head 7 is made removable from the carriage unit 15.
However, in the carriage structured in accordance with the prior art, the hook lever abuts upon the hook cover due to the biasing force of the contact spring if the hook lever is raised as shown in FIG. 14B, because the cam that has checked the biasing force of the contact spring in the direction indicated by an arrow is caused to release its engagement. Therefore, the following problems are encountered when operating the mounting and removal of a recording head.
(1) Although the removal of the recording head is possible in a state that the hook lever has been raised, it is necessary for the user to continuously operate the hook lever until the lever is positioned upward.
(2) In order to obtain the released condition just by the user's slight upward pull of the hook lever, a spring should be provided for biasing the head holder in the releasing direction. However, since the contact spring has biased the hook lever to the hook cover side, there is a need for making the biasing force of such spring greater because of the fact that resistance to slide is present between the hook lever and hook cover.
If the biasing force of the aforesaid spring is made greater in order to overcome such resistance to sliding thus existing, the biasing force of the aforesaid contact spring cannot function as the pressure acting upon the head holder through the operation of the hook lever. Therefore, the pressure of the contact spring should be made greater. Then the problem again arises that the aforesaid resistance to sliding becomes greater still.